The Adsorption And Vibration Of H And O On Transition Metal Pd Surfaces

In the heterogeneous catalysis field, the interaction between atoms and molecules with transition metallic surfaces plays a very important position. So, detailed theoretical study on the micro level and get the kinetic information of surface adsorption and diffusion is a challenging topic. With the development of chemical industry, more and more chemists and physicists have been interested in the subject. Use classical semi-empirical method, hydrogen and oxygen are selected to study the kinetic behavior of adsorption and diffusion on the transition metal palladium's smooth and defective surfaces. The calculation results not only reproduce the relevant experimental data, but also give some important information that has not been researched.The 5-parameter Morse potential (5-MP) of the interaction between H atom and Palladium surface has been constructed. The adsorption and diffusion of H on Pd low index surface is investigated with 5-MP in detail. The calculated results show that H atom is located at the hollow site of the Pd (100) surface. Threefold hollow site is the most stable site at the Pd (111) surface. Pseudo-3-fold hollow site and long bridge site are the two most stable sites at the Pd (110) surface. About the Pd (111) surface, with the coverage increasing, H atoms occupy the octahedral sites and tetrahedral sites of the subsurface. For the H-Pd (210) stepped system, pseudo-3-fold hollow sites and long bridge sites and 4-fold hollow sites on (110) terrace are all stable adsorption sites. According to the binding energy, we know that hydrogen atoms preferentially occupy pseudo-3-fold hollow sites, then 4-fold hollow sites, and then long bridge sites.Molecular dynamics simulations are performed to study oxygen adsorption and vibration on Pd low index surface and Pd (N11) (N=3,5,7,9,11,13) vicinal surfaces, which exhibit (111) steps and (100) terraces of increasing width. The Sutton-Chen many-body potential is used for the Pd surface, whereas a Morse potential was used to represent the O-Pd interaction. The oxygen-oxygen interactions are described by the Lennard-Jones potential. Obtain the specific characteristic of critical point of oxygen molecules adsorption at the metal Pd surfaces. The calculation results show that the vibration frequency of each site is repeat modest regular change but inherit the vibration mode at the low index surfaces. Get oxygen molecule's adsorption configuration at the low index surfaces. About the stepped surface (13, 1,1), oxygen molecules tilt adsorption, When increase the coverage of oxygen, the angle increase.